The prior art is replete with semiconductor devices and circuits that have selectable, switchable, and/or configurable operating states, features, devices, or elements. In many implementations, different components or circuit elements can be inserted or removed as necessary using one-time programmable (OTP) fuses. For example, OTP fuses are typically used to implement cache redundancy in SRAM devices. Such OTP fuses can be used to remove a bad column or row of memory cells and to replace the bad memory cells with a redundant column or row.
The main purpose of an OTP fuse device is to act as a conductive pathway until it is “blown”. Historically, integrated fuse devices have involved patterned metal conductive links that can be selectively “blown” or cut with a laser beam or by passing a large current through them. This process causes a portion of the link material to vaporize and a portion to melt, in much the same manner as an automotive fuse, but on a much smaller scale. Once blown, the fuse changes from a highly conductive state to a highly resistive (i.e., non-conductive) state, because the blown fuse inhibits current from flowing through and represents an open circuit to the current path.
Current semiconductor technology utilizes e-fuses made of polysilicon or metals and programmed by rupturing the conductor links. In addition to strict requirements for surrounding passivation and metals, these e-fuses are relatively large and exhibit unacceptable reliability because debris and shards can cause healing which re-closes the conductive pathway. Further, most e-fuses have high power requirements for programming.
Because the current necessary to blow a currently used fuse is significantly large, the destruction of the link material can cause collateral damage to nearby devices on the circuit. Further, due to the size of the current necessary to blow the fuse, typical semiconductor devices must provide a large amount of space for the inclusion of a relatively large current generator.
Accordingly, it is desirable to provide an integrated circuit with a fuse and method of fabricating an integrated circuit with a fuse that reduces the current required for programming, and that reduces the required size of the current source. Also, it desirable to provide a method of fabricating a fuse that employs existing procedures for the fabrication of other semiconductor device elements. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.